Any drawbacks to cold blue?

Subject is a 4" 13-3 which is at the smith having some things done. There will be more work coming up and there is no sense in a re-blue at all at this point. There are some old spots that were cold blued and are now a little pitted, and some rub marks and such.

Is there any reason to not use cold blue on it to help keep it while it waits till I'm re-employed for the rest of the work?

Is there a "favorite" cold blue, or is there one I should stay away from?

I have used Brownell's Oxpho-Blue Gel with GREAT satisfaction. It is, by far, the best cold blue I have seen or used. I did a complete single shot rifle barrel many years ago and it has held up at LEAST equal to hot blue. As with all products and processes, read the instructions and follow them for best results...

I have used Brownell's Oxpho-Blue Gel with GREAT satisfaction. It is, by far, the best cold blue I have seen or used. I did a complete single shot rifle barrel many years ago and it has held up at LEAST equal to hot blue. As with all products and processes, read the instructions and follow them for best results...

I guess cold blue is cold blue. It works in a pinch however I do not use it to pretty up a firearm. Careful with cold blue is a nasty chemical. I wear latex glove when I use it. Getting the stuff on your hands can actually do damage to your kidneys. My gunsmith friend told me some of that stuff is so nasty. He actually told me throw out all that cold blue you use on parts and I will blue your parts for free. Problem with that is I have to wait until he does bluing. That can be a few days or weeks. Heck for small stuff I still use the stuff. I'm just cautious with it.
I do not use cold blue very often. I only use it on screw heads or other small parts and small stuff like that. This is a Colt I have been playing around with. The crane lock screw was buggered up. From someone using the wrong screwdrivers. I refinished the crane screw then used cold blue to re-blue the screw cap. I can live with small nicks and scratches on my firearms. But messed up screw heads bother me those I fix. For small parts cold blue works ok for me. Here's a pic of the crane screw as it sits today. Good enough for me.

Here's a whole darn gun ("in the white") that the engraver blued with Brownells right in front of me. That stuff works! The cleaning and de-greasing took longer than the blue job. I like the end result on this type single action, but have never tried it on a long flat surface. Nasty stuff, but it works.These are the "before" and "after" photo's.